A reluctance electric machine generally includes a rotor that is rotatably disposed within a stator, wherein the stator generally includes a plurality of windings and magnetic poles of alternating polarity and the rotor is fabricated from steel or other ferrous material and preferably includes one or a plurality of inherent poles. The rotor is fabricated from ferromagnetic material such as soft iron. Torque is generated through the phenomenon of magnetic reluctance, wherein a controller controls the stator to generate a rotating magnetic field that induces a magnetic field in the rotor, and the interaction of these two magnetic fields produces torque on the rotor.
A synchronous reluctance electric machine may have an equal number of stator and rotor poles. The projections on the rotor can be arranged to introduce internal flux barriers, i.e., holes that direct the magnetic flux along a d-axis. Generally, the axis in the direction of greatest magnetic reluctance is referenced as a direct axis or d-axis, and the axis which is 90 degrees ahead of the direct axis is referenced as a quadrature axis or q-axis, which has the least magnetic reluctance. Pole numbers are known to be 4 and 6. When the spaces or notches between the rotor poles are opposed to the stator poles, the magnetic circuit of the electric machine has a low magnetic reluctance, but when the rotor poles are aligned with the stator poles, the magnetic circuit has a high magnetic reluctance. When a stator pole pair is energized, the nearest rotor pole pair will be pulled into alignment with the energized stator poles to minimize the reluctance path through the machine. Rotary motion is made possible by sequentially energizing the stator poles to cause the rotor to step to the next energized pole. The synchronous reluctance electric machine is designed to operate using an alternating current at a controlled frequency that is supplied to the stator windings. The rotor has a plurality of inherent poles to create a variable reluctance in the electric machine's magnetic circuit which depends on the angular position of the rotor. These inherent poles can be created by milling axial slots along the length of the rotor.